1. Field of the Invention
The present invention is concerned with a car-mounted equipment in which an ETC (nonstop toll collection system) and a navigation system work integrally together to share the data, making it possible to diversify the functions, to enhance the precision and to improve the reliability.
2. Prior Art
As car-mounted equipment, there have heretofore been known an air conditioner and audio equipment, as well as an ETC car-mounted unit that executes communication with an ETC on-the-road equipment, a navigation system and the like.
In particular, a well-known system can be represented by the navigation system which recognizes the absolute position of the vehicle relying upon the satellite communication (GPS) and informs the driver of data related to the position of the vehicle.
In recent years, furthermore, attention has been given to an ETC system installed at a toll gate (at the entrance or exit) of a toll road for collecting the tolls without stopping the vehicles, and a variety of systems have been proposed.
FIG. 13 is a plan view illustrating a conventional ETC car-mounted unit disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 242497/1992.
FIG. 14 is a perspective view illustrating a conventional ETC car-mounted unit together with an antenna disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 185548/1995.
Referring to FIG. 13 illustrating an ETC car-mounted unit 30, a display unit 31 functions as an output unit of the car-mounted unit 30, and a key pad 32 functions as an input unit of the ETC car-mounted unit 30.
Referring to FIG. 14 illustrating an ETC car-mounted unit 40, a cable 41 is guided from the ETC car-mounted unit 40, an antenna unit 42 is connected to the ETC car-mounted unit 40 through the cable 41, a display unit 43 is provided on the ETC car-mounted unit 40, unit switches 44 are provided on the ETC car-mounted unit 40, and an opening 45 works as a port for inserting an IC card (not shown) in the ETC car-mounted unit 40.
Conventional ETC car-mounted units 30 and 40 are constituted as shown in FIGS. 13 and 14, and offer, to the driver, at least the data related to that the vehicle is approaching the toll gate or is passing through the toll gate on the display units 31 and 43 based upon the data obtained by executing the communication with an ETC on-the-road equipment (not shown).
In general, the ETC car-mounted units 30 and 40 are realized in sufficiently small sizes, and their display units 31 and 43 are simply constituted by using LCD or LED. Therefore, it is not easily to make sure the contents of communication while driving.
Furthermore, the ETC car-mounted units 30 and 40 start (wake up) communication with the ETC on-the-road equipment upon receiving signals from the ETC on-the-road equipment, and cannot be driven at any timing. Unless data are received from the ETC on-the-road equipment, furthermore, the ETC car-mounted units 30 and 40 are not capable of displaying the name of the toll gate on the display units 31 and 43.
Moreover, a notice beacon for indicating that the vehicle is approaching the toll gate is used for shifting the ETC car-mounted units 30 and 40 from a low-power-consumption mode to a normal mode. Unless the notice beacon data is received from the ETC on-the-road equipment, therefore, the ETC car-mounted units 30 and 40 cannot be shifted from the low-power-consumption mode to the normal mode.
Unless the ETC car-mounted units 30 and 40 receive data from other unit, furthermore, the vehicle drive lane cannot be guided in a detailed manner at the toll gate. Therefore, it may become necessary to greatly change the lane near the toll gate.
The data are offered only at a timing obtained through the communication with the ETC on-the-road equipment, and the data cannot be offered at a proper timing desired by the driver.
When the name of the toll gate is to be displayed on the display units of the ETC car-mounted units 30 and 40, a table in which the names of the toll gates are corresponded to the codes must be stored in the memories of the ETC car-mounted units 30 and 40, which, however, is not easy since the ETC car-mounted units 30 and 40 have small memory regions.
On the other hand, as a means for detecting the absolute position of a vehicle used for the navigation system (not shown), there has been known an autonomous navigation system which is based upon the GPS as well as the practical traveling state of the vehicle and the map data.
When the GPS is relied upon, however, it is not allowed to distinguish whether the vehicle is traveling on an elevated toll road such as an expressway or a by-pass, or a common road under the elevated road. It is not allowed to distinguish, either, whether the vehicle is traveling on the toll road such as an expressway or a by-pass, or on a side road along therewith.
According to the prior art as described above, the ETC car-mounted units 30 and 40 and the navigation system are separately used. When the ETC car-mounted units 30 and 40 are used, which are driven in response to a notice beacon from the on-the-road equipment, it is not allowed to obtain data related to the position of the vehicle at a given timing. Besides, the display units 31, 43 and the data capacities are so small that the data are not offered to a sufficient degree.
When the navigation system is used, the position at where the vehicle is traveling can be recognized at all times by using a data base of a large capacity and a relatively large display unit, leaving, however, a problem in that it is not allowed to correctly distinguish the multi-level crossings and the adjacent by-passes.